A slide fastener provided with waterproof property (hereinafter referred to as a waterproof slide fastener) has been popularly used at an opening/closing portion or an opening formed on a product such as a bag to prevent the intrusion of a liquid such as water into the inside of the product at the time of closing the open/close portion or the opening. Here, “waterproof” means not only the prevention of intrusion of water but also the prevention of intrusion of a liquid other than water.
The waterproof slide fastener usually includes: a pair of left and right fastener stringers where an element row is formed on a waterproof tape having a waterproof layer made of a synthetic resin; and a slider which is slidable along the element rows, and also has the structure where the intrusion of a liquid into a tape back surface side from a tape front surface side (or into the tape front surface side from the tape back surface side) is prevented when the slider is slid so as to make the left and right element rows engage with each other.
With respect to such a waterproof slide fastener, various types of waterproof slide fasteners have been known conventionally. For example, U.S. Pat. No. 3,914,827 A (Patent Document 1), JP 2008-194066 A (Patent Document 2), DE 102007053020 A1 (Patent Document 3), and JP 2010-12246 A (Patent Document 4) disclose such a waterproof slide fastener.
For example, the waterproof slide fastener disclosed in Patent Document 1 and Patent Document 2 are configured such that an element row formed of coil-shaped continuous fastener elements is formed on the opposing tape edge portions (element attaching portions) of the left and right waterproof tapes. In the case of such a waterproof slide fastener where the element row is formed of coil-shaped fastener elements, when the left and right element rows are engaged with each other, the opposing tape edge portions of the left and right waterproof tapes are brought into close contact with each other so that the intrusion of water into a tape back surface side from a tape front surface side through between the left and right waterproof tapes is prevented.
Further, in Patent Document 1, there is the description that, in the waterproof slide fastener having the coil-shaped fastener elements, the fastener element and the element attaching portion of the fastener tape are covered with vulcanized silicone rubber. By covering the fastener element and the element attaching portion of the fastener tape by the vulcanized silicone rubber, when the coil-shaped fastener elements are seamed to the fastener tape, a plurality of holes (openings) formed in the fastener tape are clogged by the silicone rubber. Accordingly, the leakage of a liquid (water) to a tape back surface side from a tape front surface side through the plurality of holes can be prevented and hence, waterproof property of the slide fastener can be increased.
With respect to the waterproof slide fastener disclosed in Patent Document 2, there is the description that a water repellant agent or an oil repellant agent is applied to coil-shaped fastener elements, core threads which are made to pass through the inside of the fastener elements, and fastener tapes. Due to such applying of a water repellant agent or an oil repellant agent, for example, even when tape edge portions of left and right fastener tapes which are brought into close contact with each other are opened so that a gap is formed, the fastener elements, the core threads and the fastener tapes repel moisture or oil effectively and hence, the intrusion of moisture or oil to a tape back surface side from a tape front surface side through the gap can be prevented.
On the other hand, the waterproof slide fastener described in Patent Document 3 and Patent Document 4 is constituted such that an element row which is constituted of a plurality of independent fastener elements formed by injection-molding a synthetic resin is formed on the opposing tape edge portions (element attaching portions) of the left and right waterproof tapes.
For example, in the waterproof slide fastener disclosed in Patent Document 3, the plurality of fastener elements are fixedly attached to the opposing tape edge portions of the left and right waterproof tapes, and each fastener element is constituted of a first element half portion arranged on a tape front surface side (first tape surface side) of the waterproof tape and a second element half portion arranged on a tape back surface side (second tape surface side) of the waterproof tape.
In the fastener element of Patent Document 3, the first element half portion and the second element half portion have a face symmetry configuration with respect to the fastener tape. In making left and right element rows engage with each other by sliding the slider, the first element half portions of the left and right fastener elements are engaged with each other and the second element half portions of the left and right fastener elements are engaged with each other and, at the same time, the opposing tape edge portions of the left and right waterproof tapes are brought into close contact with each other. By bringing the tape edge portions of the left and right waterproof tapes into close contact with each other at the time of making the element rows engage with each other, liquid tightness between the left and right fastener stringers can be ensured and hence, the intrusion of a liquid to a tape back surface side from a tape front surface side can be prevented.
In Patent Document 3, a lubricant is contained in a synthetic resin used for forming the fastener element. In the waterproof slide fastener where the element row is constituted of the synthetic-resin-made fastener elements, at the time of closing the slide fastener, to make the element rows engage with each other and to bring the left and right waterproof tapes into close contact with each other as described above, it is necessary to make the slider slide by strongly pulling the left and right fastener elements to each other by making use of left and right flanges arranged on upper and lower blades of the slider.
The tape edge of the waterproof tape is arranged close to a coupling head of the fastener element and hence, when the slider is slid, a diamond which connects upper and lower blades of the slider to each other is liable to interfere with the waterproof tape. Accordingly, there exists a drawback that the slide resistance of the slider is increased at the time of closing the slide fastener. Accordingly, in Patent Document 3, a lubricant is contained in the fastener element as described previously and hence, a friction generated between the slider and the fastener element is reduced so that sliding property of the slider is improved.
In Patent Document 4, there is disclosed the waterproof slide fastener where the intrusion of a liquid through between left and right waterproof tapes is prevented by the left and right synthetic-resin-made fastener elements which are engaged with each other without bringing the left and right waterproof tapes into close contact with each other at the time of making element rows engage with each other.
To specifically explain the waterproof slide fastener disclosed in Patent Document 4 with reference to FIG. 13 and FIG. 14, the waterproof slide fastener 70 includes: a pair of left and right fastener stringers 71 where an element row 76 formed of a plurality of synthetic-resin-made fastener elements 73 is arranged on tape edge portions of left and right waterproof tapes 72 respectively; and a slider 77 which is attached to the element rows 76 and performs engaging and releasing of the left and right fastener elements 73.
The waterproof tape 72 disclosed in Patent Document 4 includes a core thread portion 72a along the tape edge. Further, a waterproof layer made of a waterproof material such as a synthetic resin is formed on a first tape surface side of the waterproof tape 72.
The fastener elements 73 disclosed in Patent Document 4 includes: a first element portion 74 arranged on a first tape surface side of the waterproof tape 72; and a second element portion 75 arranged on a second tape surface side of the waterproof tape 72, and the first element portion 74 and the second element portion 75 have the configurations different from each other.
As shown in FIG. 14, the first element portion 74 includes: a body portion 74a fixedly attached to the waterproof tape 72; a neck portion 74b projecting toward the outside of the tape from the body portion 74a and having a constricted shape such that an element width is narrowed; and a coupling head 74c further extending from the neck portion 74b and having an elongated circular shape.
As shown in FIG. 13, the second element portion 75 includes: a base portion 75a fixedly attached to the waterproof tape 72; and an element head 75b projecting toward the outside of the tape from the base portion 75a, and the element head 75b has the tapered configuration where an element width size (a size in the tape length direction) is gradually decreased toward a distal end.
In the waterproof slide fastener 70 disclosed in Patent Document 4 having such fastener elements 73, by sliding the slider 77 in the engaging direction of element rows 76, the first element portions 74 of the left and right fastener elements 73 are engaged with each other. Further, the second element portion 75 is inserted between the second element portions 75 arranged adjacent to each other on an engaging counterpart side such that the second element portion 75 is brought into contact with both neighboring second element portions 75 and, at the same time, the distal end of the element head 75b of the second element portion 75 is brought into contact with the core thread portion 72a of the waterproof tape 72 on a counterpart side.
Accordingly, in Patent Document 4, when the left and right element rows 76 are engaged with each other, the left and right waterproof tapes 72 are made to be separated from each other and hence, the increase of the slide resistance of the slider 77 can be suppressed. Further, when the left and right element rows 76 are engaged with each other, the first element portions 74 of the left and right fastener elements 73 are engaged with each other, and the left and right second element portions 75 are alternately engaged with each other such that the second element portions 75 cover a slight gap formed between the left and right first element portions 74 in an engaged state, and the distal end of each second element portion 75 is brought into contact with the core thread portion 72a of the waterproof tape 72 on a counterpart side.
By making the left and right fastener elements 73 engage with each other such that the first element portions 74 and the second element portions 75 are alternately engaged with each other and by making the left and right second element portions 75 alternately engage with each other extending over the left and right waterproof tapes 72, it is possible to prevent the formation of a straight-line-shaped gap which penetrates from an element front surface side to an element back surface side between the left and right waterproof tapes 72. Accordingly, although the left and right waterproof tapes 72 are separated from each other when the element rows 76 are engaged with each other, the intrusion of a liquid into a tape back surface side from a tape front surface side of the waterproof slide fastener 70 is minimally generated.